(1) Field of the Invention
The present invention relates to unmanned underwater vehicles adapted to travel at either high or low speed below the surface of the sea. More specifically the invention relates to providing such a vehicle with an extendible sonar array which has a forward looking capability that supplements the provision of a conventional nose mounted array in such a vehicle.
(2) Description of the Prior Art
Underwater vehicles have in the past been provided with nose mounted sonar arrays which are capable of looking forward but which forward ranging is relatively restricted due to the small overall diameter of such underwater vehicles in general.
Larger arrays have been limited to use on vertically extending cables, and although some versions of such larger diameter arrays have been designed that provide for deployment motion of the hydroplane transducers relative to the vertically oriented cable, such a feature has never been applied to high speed unmanned underwater vehicles (UUV). Scopatz U.S. Pat. No. 3,566,346, Jonkey U.S. Pat. No. 3,886,491 and Secretan U.S. Pat. No. 5,091,892 illustrate such cable mounted sonar arrays.
Also known from the prior art is the fact that control fins or stub wings have been designed to be extendible and retractable from a position parallel to the longitudinal axis of a vehicle and to extended positions where the axis of the fin or wing is oriented transversely to the vehicle axis. See for example U.S. Pat. No. 4,667,899 issued to Wedertz.
The above described disclosures do not show or suggest a system for providing an array of sonar devices that can be used in stowed positions in cavities at the sides of the generally cylindrical body portion of an unmanned underwater vehicle and in extended positions where the sonar devices provide a relatively large diameter array suitable for improved image resolution, and also capable, as a result of this increased diameter, for wider band operation generally. Underwater vehicles generally must be capable of being launched from a conventional submarine torpedo tube and therefore such external arrays have not been utilized due to the size limitations inherent from the torpedo tube diameter itself. Also the fact that external arrays generally impose a severe drag penalty on the operation of a typical underwater vehicle and, when located near the nose of the vehicle, tend to greatly reduce the stability of the vehicle has inhibited the development of such a concept.